Sofa



FIG. 1 is a perspective view of a sofa embodying my new design;

FIG. 2 is a front plan view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a right side view thereof; and,

FIG. 5 is a left side view thereof. 

The ornamental design for a sofa, as shown and described. 